This invention relates to bearing members adapted to be inserted into bearing support members by a mechanical press fit.
In mechanical assemblies involving the use of bearings and supports therefore, it is often desirable to insert the bearing member into the support member and secure it in place by means of a press fit. Such an arrangement by its simplicity inevitably results in a saving in assembly time. When the conventional sleeve type bearing is mounted in a support in this fashion, it is necessary to perform additional steps in order to insure that the diameter of the bearing surface has not changed during the manufacturing assembly. When a bearing is to be secured in a bearing support member by press fit means, the outer diameter of the bearing must be larger than the diameter of the hole in the bearing support member into which it is to be pressed. The operation of pressing the bearing into the bearing support member results in a compression of the material of the bearing and a reduced diameter of the bore of the bearing member.
In the past it has been common practice when a press fit is used to secure a bearing in a support member, to resize the bore of the bearing to restore it to its original or desired dimension. This resizing is generally accomplished by a reaming action. Where the bearing is of sintered bronze material, it has been found that reaming the inner bore of the bearing to produce the proper size sometimes results in the interstices of the sintered bronze material being closed by the reaming action and thus resulting in an impaired bearing lubrication surface.
In some instances the problem of a reduction in size of the bore has been overcome by inserting in the bearing a mandrel of appropriate diameter during the operation of press fitting the bearing into the bearing support member. With the mandrel so located in the bore of the bearing member, the dimensions of the bore cannot be changed during the press fit operation because of the presence of the mandrel. The sintered bronze material is compressed in order to provide not only the holding action with the support member but also to retain the original inner bore dimension. When the press fit operation is complete, the mandrel is then removed to provide an appropriately secured bearing member with the proper dimensioned bore. If the bearing material is other than sintered bronze and particularly a material which has an elasticity, the use of the mandrel will not provide the desired inner bore dimension because when the mandrel is removed, the compressive forces in the material of the bearing will be released and the elastic material will move to reduce the bore dimension.